Abstract: The effects of temperature (298–318 K) and pH (4.5–8.5) on the stability, antioxidant activity and bioaccessibility of β-carotene-loaded octenylsuccinated β-glucan (OSβG) micelles were investigated. Differential scanning calorimetry (DSC), thermogravimetry (TG) and derivative thermogravimetry (DTG) indicated that the peak temperature of thermal degradation of the micelles presented a parabolic trend with increasing temperature and pH, peaking at 313 K and pH 7.5. During 10 h of ultraviolet irradiation and 30 d of storage at room temperature, the micelles prepared at 313 K and pH 7.5 exhibited the lowest degradation rate and highest retention rate of β-carotene. By using the first-order kinetic and Weibull models, it was found that the degradation of β-carotene fitted well with the Weibull model, regardless of the temperature or pH used. The degradation rate showed a U-shaped trend with increasing temperature and pH. Similarly, the half maximal inhibitory concentration (IC50) of the β-carotene-loaded micelles against 1,1-diphenyl-2-picrylhydrazyl radical and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) cation radical showed a U-shaped trend, while the bioaccessibility showed a parabolic trend. All three parameters were closely related to the structural stability and compactness of micelles. Moreover, OSβG micelles enhanced the stability, antioxidant activity and bioaccessibility of β-carotene, the effect being most pronounced at 313 K and pH 7.5. This could be related to the fact that temperature and pH affected the stability and compactness of micellar structures via altering the protonation level of OSβG and the molecular interaction force between β-carotene and OSβG. This study revealed that the stability of laden micelles could be regulated by changing environmental conditions, guiding its application in different processing scenarios.

Key words: octenylsuccinated β-glucan micelles; β-carotene; temperatures; pH; structural stability